Clinical trials of investigational new drugs (INDs) involve the collection, display and analysis of large amounts of data. The present proposal is to develop a computer system for clinical trial studies that takes advantage of the unique capabilities of the Hand-Held Computer (HHC), a powerful microcomputer approximately 3" high by 8" long. The small size and light weight of the HHC makes it possible to collect and process data even at times and places where larger computers would be inaccessible, such as the homes of outpatients, or an inpatient's bedside. The HHC could provide alarms and prompts to insure that patients and nurses know when medications, assessments, and visits to the laboratory are due. The HHC can administer certain assessments itself. Data such as test results, side effects, dosages, and symptoms could be quickly recorded and automatically stamped with the date and time. After the system is developed, it will be refined and evaluated in a simulated clinical trial study. The evaluation will assess its acceptance by patients and clinical staff, the amount of time necessary to train the users of the system, and the ability of the system to obtain data in a timely, accurate way.